Wind chill factor or index has come into increasing use as an indicator of dangerous cold weather conditions both for people who may be travelling and for exposed livestock. Fundamentally, it may be defined as the cooling effect of any combination of temperature and wind, expressed as the loss of body heat in kilogram calories per hour per square meter of skin surface. The apparatus of the present invention provides a simple, trouble free indicator for wind chill factor by sensing temperature and wind velocity and combining these electrically to provide a visual indication of the wind chill factor value.